The present invention provides mesoscopic magnetic field sensors operating under normal ambient conditions which can detect weak magnetic fields (typically 0.05 Tesla) over areas as small as tens of thousands of square nanometers (e.g. 40 nmxc3x97400 nm). The combination of magneto-resistance in an inhomogeneous high mobility semiconductor, having special electrode arrangements, with the use of island lithography, enables the production of special semiconductor/metal nano-composite structures, and has made possible the fabrication of an entirely new type of magnetic field sensor which exhibits very superior magneto-resistive behavior.
Accordingly, it is a primary object of the present invention to provide mesoscopic non-magnetic semiconductor magnetoresistive sensors fabricated with island lithography and a commercially feasible method of fabricating such magnetoresistive sensors.
In accordance with the teachings herein, the present invention provides a mesoscopic magnetoresistive sensor fabricated utilizing island lithography to form an inhomogeneous high mobility semiconductor with metal inclusions in a nano-composite structure having enhanced magnetoresistance. The nano-composite structure is provided with enhanced magnetoresistance in an InSb (indium antimonide) semiconductor matrix by the addition thereto of a relatively small amount of silicon donors. The enhanced or boosted magnetoresistance in an inhomogeneous narrow-gap InSb semiconductor is combined with island lithography to provide a new type of mesoscopic magnetic sensor.